Disposable scouring pad



United States Patent 3,382,058 BISPUSABLE SCOURING PAD Louis MaxwellWise, Union, N.J., and Joseph Richard Anghinetti, Kennebunlrport, Maine,assiguors to American Cyanamid Company, Stamford, Comm, a corporation ofMaine No Drawing. Filed July 24, 1964, Ser. No. 385,079 1 Claim. (Cl.51-495) ABSTRACT OF THE DISCLOSURE Disposable scouring pad having anadhesive abrasive composition adhered to a flexible, porous base such aspaper, the abrasive being a particulate synthetic resin of a Barcolhardness of at least 33 and a particle size from about 20 to 200 mesh,where the paper substrate may be impregnated with a detergent, and aporous pad may be adhesively secured to the substrate on the sideopposite the abrasive composition.

This invention relates to the novel use of particular resinous compoundsas abrasives and their use as a component in manufacturing a disposablescouring pad. The abrasive and the scouring pad each are designed foruse for cleansing, abrasive and polishing needs. They are particularlyof value in uses such as smoothing wood and paint, the scouring andcleaning of pots, pans and other utensils and equipment in the kitchen,and the cleaning of porcelain bathroom equipment and such.

In order to have the required abrasive characteristics necessary for thescouring pad to give desired results, the abrasives utilized in priorart scouring pads included nonmetallic materials such as aluminum oxide,emery, silicon carbide, silica, pumice stone, and the like, and metalsof various hardness. The most frequent abrasive pads are steel, bronze,copper, or glass mesh scouring pads. Each of these various abrasivescarries the basic problem of scarring and scratching the substrate.

Other problems, which are just as important to the consumer, includedthe abusive effect upon the hands of the user. The fact that abrasivesof this coarse and hard nature (I) tend to readily separate from thebacking, especially during strenuous use, and (2) tend to combine withthe grease and char to produce filth unsuitable for prolonged futureuse, complicate the problem of obtaining a commercially acceptable pad.Also, the abrasive which is worked loose over a period of time tends toclog the drains of sinks. Where steel mesh is utilized, after limiteduse, rust complicates the picture.

To counter some of these problems, some manufacturers incorporate rustinhibitors, and to generally improve the cleansing efficiency, themanufacturers fre quently incorporate soap or a detergent of some sort.

Where the scouring pad consists of abrasive particles bonded to abacking with a binder, too weak a binder further complicates theproblem, mentioned above, of the coarse abrasives separating from thebacking. To give some degree of protection to the hands of the user,protection against all the harsh ingredients referred to above, variousmanufacturers have developed assorted devices such as handles and thelike.

As the problems discussed above become more complicated, and morecomplex means are employed to overcome the problems, the cost continuesto rise. Manufacturers attempted to offset increased cost by modifyingthe structures so that the scouring pad would be longer lasting for theconsumer.

It is an object of this invention to overcome the above problems byeliminating the need for the harsh abrasives discussed above, with theiraccompanying problems.

Another object is to produce a scouring pad where the 3,382,058 PatentedMay 7, 1963 danger of the abrasive becoming embedded in the hands of theuser, is overcome.

Another object of this invention is to provide an efficient scouringabrasive which does not detrimentally scar nor mar the substrate whichis being cleaned.

Another object is to produce an efficient scouring pad which is ofsufliciently low cost that after a single use, the consumer may discardthe scouring pad without suffering substantial economic loss.

Other objects become apparent from the above and following disclosure.

As discussed above, the prior art had always found it necessary to use aharsh abrasive of either non-metallic or metallic materials, such assteel, bronze, copper, or glass mesh, in order to have the requiredabrasive characteristics for scouring pots, pans, etc. In scouring padcombinations, resinous materials were sometimes used as binders forattaching the abrasive composition to a backing substrate. As contrastedto the foregoing abrasive materials conventionally used, the resinouscompounds were considered by the ordinary artisan, to have little or noabrasive action, especially in the scouring art, the scouring art beingcomplicated by the many problems as discussed above. Further evidencethat resinous compounds were considered by the prior art to beessentially nonabrasive is found in the field of dentistry, which hasutilized such resinous compounds as mild cleaning agents. For purposesof a dental cleaning agent, the substance should remove the tightlyadherent pellicle film with a minimum of abrasion of the underlyingtooth material, which includes the soft dentin which may be exposed byreceding gums. Thus, the ideal cleaning agent in dentistry is one whicheffects the maximum removal of pellicle film with the minimum abrasionof dentin. Prior to applicants invention, it would have been illogicalto suspect that a cleansing agent sufiiciently mild as to be used forthe above dental purposes, would also be effective to remove charred andtough materials such as are associated with used cooking utensils, forexample.

As contrasted to the accepted conventional view in the art, as to theseresinous compounds, it has now been un expectedly found that theresinous materials of this invention are preferred and superior scouringagents.

This invention relates more particularly to the use as an abrasive ofresinous materials for scouring purposes.

The abrasive compositions herein described may be used, not only asabrasives for scouring pads, but may be incorporated into scouringpowders, grin-ding compounds and many other uses where abrasives arenormally used.

The key to this invention is an abrasive powder with high efiiciency inremoving soil, but with less tendency to scratch the substrate than havethe usual abrasives such as silica.

When the abrasive is used in a scouring pad combination, the abrasiveparticles may be bound to a face of a substrate such as paper, using abinder such as resin.

When detergent is used as a part of a scouring pad combination, asaturating substrate such as the paper referred to above, is utilized asthe backing, whereby the detergent leaches out of the substrate facewhich is opposite from the face to which the abrasive is bound.

In a scouring pad more suitable for prolonged use, a backing of materialsuch as polyurethane or dacron wadding may be attached to the substratesuch as the paper-backing referred to above, to thereby produce adouble-backing. The backing is attached to the substrates face which isopposite to the face to which the abrasive is bound. Any stable bindermay be used to attach the backing.

When a double-backing is used, as referred to above, an additionalcombination may include a detergent conveniently incorporatedsubstantially homogenously throughout the binder used to bind thebacking to the substrate face as described above.

In the double-backing combination using a backing for the substrate andusing a detergent in the binder as described above, not all binders givedesired results, because the binding-action of the binder is broken asthe detergent leaches out. A preferred binder formulation has beendiscovered, whereby the binding-action is not broken by the leaching outof the detergent. The detergent must leach through the backing, therebyprolonging the efiective life of the detergent in the scouring pad.

It is to be understood, however, that where a doublebacking as describedabove, and a detergent are both utilized in the scouring padcombination, the detergent may be incorporated into a saturating paperas described above for the (single-substrate) paper-backed combination.

Preferred and superior results are obtained with (l) a polyester of thetype which is cross-linked With an allyl monomer, and (2) an aminoplastcompound bis(methoxymethyl) methylol melamine.

The preferred allyl monomer is triallylcyanurate which is reacted withmaleic anhydride and ethylene glycol. The triallylcyanurate is of thestructural formula:

The bis (methoxymethyl)methylol melamine is a reaction product of thecharacteristic formula:

(Melamine) (CH OH CH OCH y where X is: [a] H; or [b] CH Where Y is: [a]-CH or [b] C H or [c] C H or [d] combination of these types and where atypical example is polymethyl methacrylate of the generic structuralformula:

[2] allyl and allyl-modified resins, such as diallyl phthalate, and thepreferred triallylcyanurate discussed above,

[3] polycarbonate formula:

resins of the generic structural CIIHa, 1Q CH;

4 [4] cellulosic resins of the generic structure formula:

X l 0 r CH-O {-03 oH-o]..

(DH-(3H o o l I Y 2 wherein X,YandZare:

0 [a] CH3; or [b] CaHal -o=o 0 [0] C3H7-C where:

n, p, r and t are each greater than one, and n+1 is greater than three.

[6] polyacrylonitrile resins of the generic structural formula:

(1N [-CH OH]u (b) Acetal resins, of the generic formula:

[O--CH -OCH (c) Chlorinated polyether resins of the generic structuralformula:

(Jul-01 [O-CHg-CCHz-] (d) Styrene resins, such as: [1] styrene polymers,of the generic structural formula:

[2] styrenc-acrylonitrile copolymers, of the generic structural formula:

[3] styrene, butadiene, acrylonitrile copolymers of the genericstructural formula:

(e) Epoxy resins, of the generic structural formula:

(f) Phenoxy resins, of the generic structural formula:

(g) Phenolic resins, such as phenol-formaldehyde, of the genericstructural formula:

(HOHOM where n is at least 1.5.

(h) Vinyl polymer and copolymer resins, of the generic structuralformula:

Where X is H or Cl, and

(i) Polyamide resin, of the generic formula:

{-NH(CH2)DNH -(CH2)1' ]X Where:

p and r each equals 2 to 10, and X equals 20 to 1500.

(j) Cellulosic resins, of the generic structural formula:

Where X, Y and Z are: [a] -H; or [b] C H or [c] mixtures thereof.

The aminoplast compounds of this invention include compounds such asmelamine-formaldehyde resin or melamine-glyoxal resin, urea-formaldehyderesin or ureaglyoxal resin, protein resins such as casein-formaldehyderesin, and the methylol and alkylated methylol resin derivatives of:

(a) Urea analogues of the generic formula:

where X is: O (urea), or S (thiourea), or =NH (guanidine).

(b) Ethylene urea:

CHr-NH o OHa1 IH (c) modified ureas:

CHz-NH X c=o (HrfiH where X is:

[1] CH (trimethylene urea), or

[2] R-N (tetrahydrotriazinones),

where R=alkyL (d) Acetylenediurea:

NHCHNH I IHGH-I II-I (e) Melamine and substituted melamines:

urn-( 3 R2 Where R, R and R are H or alkyl.

(f) Guanamines:

I! c ONE-R1 Where R is H, alkyl, or substituted alkyl.

(g) [1] Monoand [2] di-carbamates:

NHr-O where R is alkyl, and

HzN O-RO -NI-IR1 Where R is alkylene and R is H or alkyl.

(h) 4,5-dihydroxyimidazolidinone and its ethers:

where R and R are H or alkyl,

(i) Bispropionamides:

A limiting factor in the choice of any resinous abrasive for purposes ofthis invention, is the requirement that the resinous abrasive be of atleast 33 Barcol hardness.

A preferred embodiment of this invention is the incorporation of theabove abrasive (Barcol hardness of at least 33) into a scouring pad, theabrasive being attached by a binder to the substrate. In themanufacturing of a disposable scouring pad, the abrasive treatment inapplying theparticulate abrasive to the substrate such as paper,

may be applied by various means such as (1) during the papermanufacture, or (2) by dipping, (3) coating, (4) spraying, etc. Also, asnoted above, a backing material such as polyurethane or Dacron waddingmay be bound to the substrate, to form a double-backing. When thisabrasive is utilized with one or more of particular binders and aparticular substrate, a scouring pad combination of unexpected superiorefiiciency results, when using solids of about 5% to about 30% ofabrasive and about 30% to about 40% of binder, the percentages beingbased on total weight prior to application to the substrate.

For the permeable-plastic double-backing embodiment described above, thedetergent percentage is flexible, depending upon (I) the particularbacking used, (2) the location of the detergent, i.e., in the paper oralternatively in the adhesive binding the backing to the paper. (3) theintended use and intended longevity of the scouring pad, etc. However,the preferred detergent range is about 19% solids and the detergent mayadditionally include about 2.5% to about 50% of an organic or inorganicacid such as citric acid and monosodium phosphate, the percentages beingbased on the total weight of the composition before its application tothe double-backing substrates. For the paper-substrate embodimentwithout a double backing, the detergent solids preferably is about 6.7%,and may additionally include about 3.3% of an inorganic or an organicacid such as citric acid and monosodium phosphate, the percentages beingbased on the total weight used of the composition before application tothe saturating paper.

For the paper backed pad, we prefer a ratio of detergent to monosodiumphosphate of 2:1. This is applied at the rate of about 0.06 lbs. ofsolids/sq. yd. of paper.

For the double backed pad, the adhesive-detergent mixture is applied atthe rate of about 0.915 lbs. of formulation/sq. yd.

The abrasive resin of this invention is effective as a scouringcomposition only within a critical particle size range of about 20 toabout 200 mesh. The upper limit of particle size is dictated (1) bymanufacturing considerations, and (2) to avoid excessive scratching,rather than determinants related to effectiveness as a scouring agent.The preferred range is from about 40 to about 140 mesh. The optimumparticle sizes within these ranges also vary, depending upon thesubstrate to be scoured, and upon the form when used, such as whenattached to a flexible backing.

The adhesive used in the scouring pad combination to attach theparticles to a flexible substrate, should preferably be elastic,flexible, and resistant to deterioration by hot water, soap, detergents,acids, etc. However, with these practical considerations in mind, anyconventional glue or adhesive may be used, such as rubber cement, orpyroxylin. Gum arabic, gum tragacanth, gum congo, gum karaya, gum kauri,gum sanadrac, and soybean gum, are sensitive to water and are suitableonly for dry scouring conditions. It is within the scope of theinvention to use conventional resinous adhesive formulations known tothe ordinary artisan.

The unexpectedly superior results are obtained by the use of emulsionsof polyvinyl acetate, or thermoplastic acfylic polymers and copolymers,or mixtures thereof. These preferred adhesives are illustrated inExamples 2 and 9.

Another particularly desirable adhesive is a butadiene acrylonitrilecopolymer blended with a phenol aldehyde resinous condensation productin the proportion of about 70 parts of the said copolymer to parts ofthe phenolic resin dissolved in a suitable solvent.

The detergent used in a scouring pad combination of this invention maybe anionic or cationic or nonionic, and may include any one or moreconventional detergents, such as sodium or amine dodecylbenzenesulfonates, sulfated fatty esters, sodium alkyl naphthalene sulfonates,sodium dodecyl diphenyl ether disulfonate, ethylene oxide condensates offatty alcohols, ethylene oxide condensates of alkyl phenols, ethyleneoxide condensates of alkyl amines, fatty esters of polyhydroxyalcohols,fatty alkanolamides, and fatty glyoxalidines.

The detergent-binder composition which gives unexpectedly superiorresults when in a scouring pad combination which uses the plasticbacking referred to above, is made from an emulsion containing about atotal of 37% solids. The solids of the emulsion include substantialreactant percentages of polyethylacrylate, methacrylate, and methylolacrylamide. The detergent-binder composition contains about 60 parts ofthe emulsion, about 27 parts of sodium dodecylbenzene sulfonate, about13 parts of monosodium phosphate, about 1.6 parts of coconut fattyacidethanolamine condensate, about 10 parts of glycerine and about 30parts of water.

Any conventional method known in the art may be utilized in preparingthe abrasive of this invention. However, there are preferred methodsillustrated in Examples 1 and 8, which give superior results in thepreparation of the two preferred and superior abrasives of thisinvention such as:

(1) A polyester of the type which is cross-linked with an allyl monomer(triallylcyanurate), and

(2) Bis(methoxymethyl)methylol melamine.

In order to illustrate this invention, Examples 1 through 8 illustratethe preparation of two preferred resins, the tests conducted todemonstrate their abrasive and scouring efficiency, and the resultsthereof. Examples 9' and 10 respectively, illustrate singleanddouble-backed pads, respectively. These examples do not limit the scopeof this invention, but are solely for illustrative purposes.

Example 1 illustrates the preparation of the preferred polymerizedpolyester resin for use as a scouring abrasive.

Example 2 illustrates preparation of abrasive-detergent paper using thepolyester resin of Example 1.

Example 3 illustrates the application of an acidified detergent to theback of the treated paper prepared in Example 2.

Example 4 illustrates the preparation of the resin dye panels to be usedin the scouring tests of Examples 5 and 9, testing the abrasive papersof Example 2, Example 3, and Example 9.

Example 5 illustrates the scouring test and results for the abrasivetreated paper of Examples 2. and 3.

Example 6 illustrates an abrasive test, of the preferred polyesterresin, to determine the abrasive action on stainless steel.

Example 7 using the preferred polyester resin, illustrates (1) scouringefficiency and (2) abrasive efliciency, on a charred aluminum skillet.

Example 1.Preparation of polymerized polyester resin To grams of thepreferred triallylcyanurate crosslinked polyester resin in the form ofan aqueous syrup (of about 80% resin solids) was added 1.0% benzoylperoxide. This was heated to 60 C. for about 15 minutes to dissolve thebenzoyl peroxide. The resultant product was poured into a stainlesssteel pan to a layer about Ms" thick and then cured at C. for an hour.After cooling, the resultant solid was broken into small parts andmicro-milled to obtain particles of from 40 to 200 mesh. The resin syrupincludes a reaction product of maleic anhydride, ethylene glycol, andtriallylcyanurate.

Thus, Example 1 illustrates the method used to prepare the preferredresin for testing.

Example 2.Preparation of abrasive paper using polyester resinapplication of resin-binder composition Five parts of polyester resinmicro-milled as shown for coating No. 1, in Example 1, was mixed with 20parts of 55% solids emulsion of polyvinylacetate copolymer. A film of 10mil. thickness of this mixture was knife coated on one side of a 0.025inch thickness, white, saturating paper. The thus treated paper was thendried for 10 minutes at 225 F.

Example 3.Application of acidified detergent (single, paper-backed) Theopposite side of the above treated paper (of Example 2) was sprayed with8 parts of an aqueous solution containing alkylaryl sulfonat e and 0.5%monosodium phosphate. (However, about 6.7% of alkylaryl sulfonate andabout 3.3% of monosodium phosphate is preferred.) The treated paper wasthen dried for 10 minutes at 225 F.

Thus, Example 3 illustrates treatment of the Example 2 paper, treatingthe back side with an acidified detergent. This paper is for use intests of Examples 5, 6 and 7.

Example 4.-Method of preparing resin dye panels used in abrasion testsThere are two separate coatings.

I. Coating l.-Into a ball mill was entered 358.5 parts of a petroleumdistillate solvent. To this was added 801 parts of calciumcarbonate-titania, 204 parts of rutile type titania, 255 parts powderedclay, 85.5 parts diatomaceous earth, 3.45 parts aluminum stearate and564 parts alkyd resin containing phthalic anhydride and soya type oil.Small steel balls weighing 3000 grams were added to the mixture toassist in milling. The mixture was milled for two days and then 2.7parts of 6% cobalt naphthenate and 8.25 parts of 24% lead naphthenatewere added. The milling was then continued for an additional 30 minutes.

A portion of the above mixture was knife coated onto an aluminum panel,imparting a 0.0015 inch thickness film. The panel was then air dried for30 minutes followed by a subsequent heat treatment at 350 F. for 10minutes in a circulating hot air oven.

II. Coating 2.A resin-dye solution was prepared wherein 0.5 parts of (1)an anthraquinone type oil blue dye was dissolved, (2) in 240 parts of apetroleum distillate solvent and 83 parts of this solution was mixed (3)with 400 parts of a 65% solution of polymerized terpene resin inpetroleum solvent.

A 0.0015 inch thickness film of this resin-dye composition (type IIcoating) was applied over the previous coating (type I coating), airdried for 30 minutes, followed by a subsequent drying at 350 F. for 10minutes.

Thus, Example 4 illustrates the preparation of resin dye panels to beused to test scouring efiiciency in Examples 5 and 9.

Example 5 A portion of the treated paper of Example 2 was attached tothe abrasion boat of a Gardner Washability Machine and permitted toabrade an aluminum panel coated as in Example 4, employing 50 strokesduring which time the panel was kept wet with distilled water. The panelwas then compared for scouring efiiciency (the degree of removal of thesubstrates coating material) with a series of arbitrary standards inwhich zero is poor and a rating of 6 is excellent.

The scouring efliciency of this trial was rated 5 (very good).

Thus, Example 5 illustrates the scouring test and interpretation ofresults, for the treated abrasive paper of Examples 2 and 3, when testedon the resin dye panels of Example 4.

Example 6.-Test for surface damage to stainless steel The procedure ofpreparation of Example 5 is followed with the exception that the panelabraded was uncoated stainless steel. The panel after 50 strokes wascompared for scratches with a series of arbitrary standards in whichzero is excellent (showing no scratches) and 5 is poor (showing a badlyscratched surface).

The scratch rating with the abrasion paper of Example 2 was zero,showing no scratches.

Thus, Example 6 illustrates the abrasion. test and interpretation ofresults, for the treated abrasive paper of Examples 2 and 3, when testedon an uncoated stainless steel substrate.

Example 7.Practical scouring test In this experiment the abrasive papertreated as Example 2 was used as follows:

Ordinary margarine was placed in an uncoated aluminum skillet and heateduntil it burned, leaving the skillet in a dirty brown and cakedcondition. The skillet was then scoured wet with a portion of the papertreated as in Examples 2 and 3.

Results in the skillet show (1) scouring efficiency was good, and (2)essentially no damage to the aluminum surface, the abrasion scratchrating was good.

Thus, Example 7 illustrates the use of a margarineburned aluminumsubstrate to test scouring efficiency and abrasive scratch rating forthe treated abrasive paper of Examples 2 and 3.

Example 8.Preparation of polymerized aminoplast resin To 100 grams ofbis(methoxymethyl)-methylol melamine resin aqueous syrup (of about resinsolids) was added with stirring 10 ml. of 37% hydrochloric acid. (Thisexotherms to about 40 C.) The resultant product was poured into astainless steel pan and let stand two days at room temperature at whichtime a solid material was formed. The resultant material was broken intosmall parts and micromilled to obtained particles of from 40 to 200mesh.

Thus, Example 8 illustrates the preparation of the preferred,polymerized aminoplast resin, bis(methoxymethyl)-methylol melamine.

Example 9 This example illustrates a single, paper-backed pad.

An aqueous mixture containing 1 part of the pulverized aminoplast resinof Example 8, and 4 parts of a 55% polyvinylacetate copolymer emulsionwas applied to one side of white wet strength absorbent paper by knifecoating, thereby imparting to the paper a 10 mil film of the mixture.The coated paper was dried for 10 minutes at 225 F. The back of thepaper was then saturated with a solution containing 10% sodium alkylarylsulfonate and 0.5% monosodium phosphate followed by drying as previouslymentioned. (However, about 6.7% of sodium alkylaryl sulfonate and about3.3% of monosodium phosphate is preferred.)

Samples of this paper were evaluated for scouring and abrasionefficiency as described in Examples 5 and 6.

Under the standard method of evaluation as aforementioned the ratingswere as follows:

Test: Rate Scouring (cleaning) 6=excellent Abrasion (scratching0=excellent Thus, Example 9 illustrates the scouring test and results,and the abrasive scratch test and rating, when using the abrasive resinpreparation of Example 8, using substrates as prepared in Examples 5 and6.

Example 10 This example illustrates the preparation and use ofapplicants preferred double-backed scouring pad.

A scouring pad was prepared by the procedure of Example 9, using thepreferred 6.7:3.3 ratio of sodium alkylaryl sulfonate; monosodiumphosphate and using paper which had been treated with a wet-strengthresin.

1 1 The following materials were mixed together:

Parts Emulsion of thermoplastic acrylic copolymer (31% solids) 70Coconut fatty acid-ethanolamine condensate 1.6 Glycerol 7.5 Sodiumdodecylbenzene sulfonate 20 Monosodium phosphate Water 33 Thisformulation was applied to the back of the paper by means of a coatingknife at the rate of 0.92 lbs. of formulation/sq. yd. A sheet ofpolyurethane foam thick was placed over the coating, pressed down firmlyand dried for 8 min. at 275 F.

This pad was used for scouring small pans. Between uses it was rinsedand permitted to dry. On each use, it generated copious foam and thepolyurethane foam showed only slight tendency to separate from the restof the pad.

Although the invention has been described in detail with reference tocertain preferred embodiments, thereof, it will be understood thatvariations and modifications can be effected Within the spirit and scopeof the invention as described above and as defined in the appendedclaim. It is, for example, within the scope of this invention to add anyof various conventional perfumes, disinfectants, coloring and bleachingagents, etc. to the abrasive or to the combinations disclosed.

What is claimed is:

1. A scouring pad combination comprising a Wet strength paper substratehaving applied to one side a thin layer of a scouring compositioncomprising in parts by weight (1) about 5 parts of a particulatesynthetic resin having a Barcol hardness of at least 33 and a particlesize of about 20 to 200 mesh, said resin being selected from the groupconsisting of triallylcyanurate polyester resin andbis(methoxymethyl)-methylol melamine resin, and (2) about 20 parts of apolyvinyl acetate polymer emulsion having solids, said substrate havingapplied to its other side a layer of a detergent binder compositioncomprising (1) about parts of an emulsion of a thermoplastic acryliccopolymer containing 31% solids, comprising polyethylacrylate,methylacrylate and methylolacrylamide, (2) about 1.6 parts of a coconutfatty acidethanol amine condensate, (3) about 7.5 parts of glycerol, (4)about 20 parts of sodium dodecylbenzene sulfonate, (5) about 10 parts ofmonosodium phosphate, and (6) about 33 parts water; said detergentbinder composition layer having a pad of polyurethane foam securedthereto.

References Cited UNITED STATES PATENTS 2,665,528 1/ 1954 Sternfield etal. 51295 3,014,795 12/ 1961 Schmidlin 51298 3,050,414 8/1962 Reilly51-296 3,116,574 1/ 1964 Ciesielski 51295 3,251,800 5/1966 Cooley et al.51296 3,261,675 7/1966 Cameron 51295 3,266,878 8/1966 Tinimer et a1.51-298 ALEXANDER H. BRODMERKEL, Primary Examiner.

DONALD J. ARNOLD, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,382,058 May 7, 1968 Louis Maxwell Wise et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4, line 25, beginning with "where:" cancel all to and including"three." in line 28, and insert instead the following:

or [d] -NO or [e] mixtures of these; where examples of the cellulosicsare cellulose acetate, and cellulose acetate butyrate, [5] alkyd resinswhich are condensation where n, p, r andt are each greater than one and,where n r is greater than three.

Signed and sealed this 11th day of November 1969.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents

